Eratosthenes (276–194 BCE)
Eratosthenes was a Greek astronomer, geographer and mathematician who was born in Cyrene (in modern Libya). He studied in Athens, where he wrote several poems and historical works, and subsequently moved to Alexandria at the age of 30 to work at the library (the most important such institution of the ancient world) at the invitation of Ptolemy III.
He spent the remainder of his life there. After a few years, he was elevated to the position of Chief Librarian. While he was there, he studied and wrote scholarly works in several different fields; all have been lost, but we know of the breadth of his endeavours due to numerous references by succeeding scholars. His three-volume work Geography was of huge importance – he perceived the earth to be a globe, devised and used a system of latitudes and meridians to describe it, and calculated the circumference of the earth to be 250,000 stadia (there were 8 stadia to the Roman mile), remarkably close to the actual measurement. Unfortunately, none of his works survived to the present day, but there are over 150 fragments preserved through other authors. In the last years of his life he became blind, which left him unable to study and so depressed him that he ultimately starved himself to death.More on the topic Eratosthenes (276–194 BCE):
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